The potential repair of articular cartilage in human using porous scaffolds has been described. Mears in U.S. Pat. No. 4,553,272 describes a method for osteochondral repair focusing on the use of starter cells, specific pore sizes in a porous scaffold, and providing a barrier between the two pore sizes. There is no mention of the use of biodegradable scaffolds or the necessity of providing a scaffold that can withstand physiological loads. Hunziker in U.S. Pat. No. 5,206,023 teaches a method for articular cartilage repair involving pretreating the defect area with enzymes to remove proteoglycans, then providing a biodegradable carrier (scaffold) to provide proliferation agents, growth factors, and chemotactic agents.
Vert et al. in U.S. Pat. No. 4,279,249 describe a solid biodegradable osteosynthesis device made of a fiber-reinforced composite. The fibrous component is a biodegradable polymer high in glycolide content and the matrix component is high in lactide units. There is no mention of porous devices and the favorable mechanical properties achieved through fiber reinforcement are obtained through typical stacking and layering techniques known in the art. Uniform distribution of fibers throughout the matrix is not disclosed.
The prior art does not appear to teach how to optimize mechanical properties by reinforcing highly porous materials (50%-90% porous). Nijenhuis et al. in European Patent 0 277 678 describe a biodegradable, porous scaffold preferably incorporating biodegradable reinforcing fibers. The scaffold has a bi-porous structure (bimodal pore distribution) made using a combination of solution-precipitation and salt-leaching techniques. Although the fibers are incorporated to “reinforce” the scaffold, no evidence is presented to verify that the mechanical properties are actually improved through such reinforcement and the fibers appear to be randomly aligned.
Stone et al. in U.S. Pat. No. 5,306,311 describe a prosthetic, resorbable articular cartilage composed of a dry, porous, volume matrix of randomly or radially oriented, allegedly biocompatible and bioresorbable fibers. Stone's patent speaks mainly of natural polymeric fibers, such as collagen and elastin, which are harvested and purified from xenogenic sources. The fibers are then cross-linked to provide a cohesive scaffold. The ability of the scaffold to support articulating joint forces is not shown.
All publications and patent applications referred to herein are fully incorporated by reference to the extent not inconsistent herewith.